1. Field of the Invention
The invention relates to an improved air filter as defined in the preamble of claim 1.
2. Description of the Related Art
Prior known from the present Applicant's earlier European patent application EP 2275187 is an air filter intended for an air conditioning system, comprising a disc-like filter element and a power unit, preferably an electric motor, that is connected to the filter element for rotating it. The filter element is arranged in connection with a ventilation duct, such as outside an aperture of the ventilation duct, at a distance therefrom and concentrically with the ventilation duct. Air is supplied by way of the air filter and the aperture into the ventilation duct.
A problem with the air filter is that the rotating filter element spreads a major portion of the impurities back in the air, thus circulating the same e.g. in indoor air.
One option for solving the problem is to provide around the air filter a collecting tank, such as disclosed in the above-mentioned European patent application. This provides a capability of collecting and removing liquid impurity droplets in and out of the collecting tank, but small solid particles swirl within the air flows of the collecting tank and the filter element, and spread back into indoor air. In the worst case, at least some of the filter element's holes are clogged by small impurity particles